1. Field of Invention
This invention relates generally to the mechanical and electrical structure of the thermal inkjet drop ejectors.
2. Description of Related Art
A conventional thermal inkjet transducer array is essentially a large bank of thin-film resistive heaters electrically connected in parallel. In particular, a thermal inkjet printer comprises an array of drop ejectors. Each drop ejector has an ink channel having an inlet end and a nozzle end and contains a resistive heater. The nozzle end of each resistive heater in the array of drop ejectors is connected to a common electrical bus, which in turn is connected to an electrical power supply providing a printer operating voltage. Each individual drop ejector is driven to eject a droplet of ink by grounding an inlet end of the resistive heater through an individually-addressable driver transistor.
The common electrical bus should be narrow, so that the length of the ink nozzle can be kept as short as possible. This tends to increase drop ejection energy efficiency. To reduce the electrical series resistance of the common bus, it is desirable to make the common bus relatively thick. Often, the common bus will have two or more layers of metal and/or polysilicon.